1. Field of the Invention
The present invention relates to a magnetic head which is suitable for a hard disc device, a magneto-optical disc device, or other such devices.
2. Description of the Related Art
Currently, rewritable hard disc and magneto-optical disc devices employ a floating-type magnetic head in order to improve reliability. FIG. 1 illustrates the construction of a typical magneto-optical disc device 1, with the cabinet removed. The magneto-optical disc device 1 rotates a rewritable magneto-optical disc 11 using a spindle motor 12. An optical pickup 13 is positioned below the magneto-optical disc 11, and a floating-type magnetic head 14 is positioned above the disc 11.
The optical pickup 13 and the floating-type magnetic head 14 are mounted on a movable block 15, which is attached to a sliding portion 17 of a linear motor 16. Accordingly, the optical pickup 13 and the floating-type magnetic head 14 can move linearly along the radius of the magneto-optical disc 11. The optical pickup 13 receives light emitted from an optical block 18 via a prism 19 inside the movable block 15. The light reflected onto the magneto-optical disc 11 is received via the optical pickup 13 and the prism 19 by the optical block 18. The spindle motor 12, the linear motor 16, and the optical block 18 are fixed on a chassis 20.
FIG. 2 illustrates an underside view of the floating-type magnetic head 14 with a flexure 24 which works as an cantilever spring-type holder. With the magnetic head 14, a load beam 22 which works as a flexible arm, is attached to the top of a stabilizing piece 21, which stabilizing piece 21 is attached to the movable block 15 (FIG. 1). An opening 23 is formed at the root of the load beam 22 and determines an appropriate spring constant of the load beam 22. The stabilizing piece 25 of the flexure 24 is attached to the top of the load beam 22 by, for example, spot welding. A slider 28 is attached to a flat-spring-shaped displacement portion 27 which is built onto the underside of the stabilizing piece 25. A magnet 29 is positioned in the slider 28, and information is recorded onto the magnetic recording material of the optical-magneto disc 11 using a magnetic field which is generated by the magnet 29.
Referring to FIG. 3, three sides of the displacement portion 27 are cut with an appropriate width and length from the middle of the stabilizing piece 25, and one end of the displacement portion 27 is combined with the vertical portions 30 of the stabilizing piece 25. In other words, the displacement portion 27 forms a cantilever spring. Such displacement portion 27 is made thin from, for example, stainless steel, and has a predetermined spring constant. As shown in FIG. 4, a projection, for example, an embossed (spherical concaved) portion 31 is formed at the middle of the displacement portion 27. The embossed portion 31 is in contact with the base 36 of the load beam 22, and works as a pivot when the slider 28 is floating due to buoyancy F generated by moving air which is produced by the rotation of the optical-magneto-disc 11. The buoyancy F of the slider 28 is transmitted via the embossed portion 31 to the load beam 22, and the load beam 22 is thereby displaced due to the buoyancy F, making the floating of the slider stable.
Another floating-type magnetic head 14 (FIG. 1) has a straddle-mounted, spring-type flexure 32 as shown in FIG. 5. The flexure 32 is integrally molded together with the load beam 22 at the end of the load beam 22. A displacement portion 33 where the slider 28 is attached, is formed onto the middle of the flexure 32, and both sides of the displacement portion 33 are combined with the ring-shaped frame 35 by hinges 34A and 34B. Both sides of the frame 35, each of which forms a right angle to each of the hinges 34A and 34B, respectively, are combined with the load beam 22 by hinges 34C and 34D. In other words, the displacement portion 33 is formed into a flat straddle-mounted spring. As shown in FIG. 6, the displacement portion 33 is terraced downward with respect to a base 36 and is formed thick by half etching and so on, so that the displacement portion 33 does not interfere with the frame 35 when the displacement portion 33 is rotated due to the buoyancy F of the slider 28.
As described above, only the one end of the cantilever spring-type flexure 24 (FIG. 4) is combined with the stabilizing piece 25 by the vertical portions 30. Accordingly, with a non-contact start-and-stop-type device, when there is a shock, in particular a vertical shock to the load beam 22 in an aslant rising position on standby, the vertical portions 30 or the displacement portion 27 may be accidentally plastically-bent.
Further, because the straddle-mounted spring-type flexure 32 (FIG. 6) is integrally molded together into the load beam 22, the shape of the flexure 32 is determined according to the shape of the load beam 22. For example, it is impossible to form the flexure 32 which is wider than the load beam 22. Moreover, in order to establish the spring constant of the flexure 32 at a predetermined value, the half etching by which the base 36 of the load beam 22 is thinly formed, takes much time and labor. Moreover, the slider 28 does not have a pivot and the buoyancy F is not effective at one point of the slider 28, and this makes the floating unstable.
An object of the present invention is to provide an improved floating-type magnetic head which increases strength and durability against shock, making the floating of the slider more stable.
In one aspect, a floating-type magnetic head according to the present invention is comprised of an arm, a slider, a magnet, and a holder. The arm is positioned slidably along the radius direction of a disc. The slider is attached to the top of the arm and floats due to the movement of air produced by rotation of the disc. The magnet is mounted on the slider. The slider is attached displaceably to the arm by the holder. With such magnetic head, a straddle-mounted spring-type displacement portion is formed on the holder which is constructed separately from the arm. A projection is built on the displacement portion so as to be in contact with the arm in order to work for a pivot of the displacement portion.
In another aspect, a floating-type magnetic head according to the present invention is comprised of an arm, a slider, a magnet, and a holder. The arm is positioned slidably along the radius direction of a disc. The slider is attached to the top of the arm and floats due to the movement of air produced by rotation of the disc. The magnet is mounted on the slider. The slider is attached displaceably to the arm by the holder. With such magnetic head, a straddle-mounted spring-type displacement portion is formed on the holder which is constructed separately from the arm. A projection is built onto the arm so as to be in contact with the displacement portion in order to work as a pivot for the displacement portion.
In still another aspect, a floating-type magnetic head according to the present invention is comprised of an arm, a slider, a magnet, and a holder. The arm is positioned slidably along the radius direction of a disc. The slider is attached to the top of the arm and floats due to the movement of air produced by rotation of the disc. The magnet is mounted on the slider. The slider is attached displaceably to the arm by the holder. With such magnetic head, a straddle-mounted spring-type displacement portion is formed onto the holder which is integrally molded together with the arm. A projection is built onto the displacement portion, in order to work as a pivot of the displacement portion. A contact portion is attached to the arm so as to be in contact with the projection.
In yet another aspect, a floating-type magnetic head according to the present invention is comprised of an arm, a slider, a magnet, and a holder. The arm is positioned slidably along the radius direction of a disc. The slider is attached to the top of the arm and floats due to the movement of air produced by rotation of the disc. The magnet is mounted on the slider. The slider is attached displaceably to the arm by the holder. With such magnetic head, a straddle-mounted spring-type displacement portion formed on the holder which is integrally molded together with the arm, and a contact portion with a projection which works as a pivot for the displacement portion, are attached to the arm.
Preferred embodiments of the invention include the following features. Referring to FIG. 7, with the floating-type magnetic head 14 according to claim 1 of the present invention, a load beam 22, working as an arm, and a flexure 40, working as a holder, are separately constructed from stainless steel. The flexure 40 is attached to the base 36 of the load beam 22 by, for example, spot welding. As shown in FIG. 8, a projection, for example, an embossed (spherical concaved) portion 44 is formed onto the middle of the displacement portion 41 and is in contact with the base 36 as shown in FIG. 9.
With the floating-type magnetic head 14, because the flexure 40 is stiffer and stronger than a conventional cantilever spring-type flexure 24 (FIG. 2), it is possible to prevent the displacement portion 41 from being bent even when there is a shock to the magnetic head 14 when it is on standby. Further, the slider 28 uses the embossed portion 44 as a pivot, making the floating more stable.